Caliper and cantilever brakes are commonly used on bicycles. Both of these types of brakes utilize brake blocks consisting of a brake pad and a brake pad mounting structure for attaching the brake blocks to caliper or cantilever brake arms in operative engagement on opposite sides of a bicycle wheel rim. Upon actuation, opposing cantilever or caliper brake arms move the contact surface of the brake block into abutment on opposing sides of the bicycle rim to stop rotation of the rim relative to the brake. The contact surface corresponds to a leading surface of a brake pad of the brake block. It is known that varying the composition of the material comprising the brake pad varies the frictional properties of the brake pad. It is also known to vary the texture or form of the leading surface of the brake pad to alter the frictional characteristics, somewhat similar to variations in the tread design of a tire.
It is known in the art that varying the frictional characteristics of the brake pad can optimize braking performance under differing circumstances. For example, under wet braking conditions it is generally preferable to use a brake pad of a soft elastomeric material which may be embedded with silicon dioxides or other friction abrasives to maximize the coefficient of friction. For dry braking, harder elastomers are generally preferred, and these harder elastomers are often impregnated with clay or graphite which lowers the coefficient of friction so as to provide for smoother stopping.
It has been recognized in the art that it can be desirable to combine brake pad segments having desired frictional characteristics to improve performance under both wet and dry conditions which can be encountered during a ride. For example, Everett, U.S. Pat. No. 5,555,959, teaches a brake pad assembly for a bicycle having first and second pad portions formed of different elastomeric compounds for imparting different frictional characteristics to a brake shoe pad, with the first and second portions being molded as a unitary brake pad member. However, the structure of Everett does not allow a user to interchange brake pad segments so as to optimize brake pad performance in accordance with the user's personal preferences or in accordance with the particular environment in which the user rides. For example, with the development of side pull cantilever brakes (commonly known as "V-brakes"), riders experience significantly greater mechanical advantage when applying their brakes than are experienced with conventional cantilever and caliper brakes. Because of this increased rim grabbing power, it would be desirable to provide riders with the option to customize a combination of brake pad segments to compensate for the increased rim gripping power, particularly as the rider's environment varies between wet and dry conditions. Unfortunately, Everett provides only manufacturer selected characteristics for the brake pad. Moreover, because the structure of Everett teaches integrally molded brake pad assemblies of different hardness, the respective segments will necessarily wear at different rates. If a user is not careful to replace the brake pad assembly as the softer brake pad segment wears, braking ability can be seriously impaired, creating a danger to the rider, particularly under wet riding conditions. Thus, the entire brake pad assembly must be replaced at significant cost even though the harder pad segments may be in excellent condition.
Other prior art teaches a brake pad consisting of hard and soft rubber for varying frictional characteristics. For example, French Patent No. 818,322, teaches a brake pad having a series of alternating soft rubber and hard rubber strips which are molded into a desired shape. French Patent No. 818,322, like Everett, does not provide the user with the ability to vary the frictional characteristics of the brake shoes by substituting brake pad segments.
Similarly, French Patent No. 1,135,068, teaches a brake pad having a soft rubber portion over two-thirds of the length of the pad with a leather portion over one-third of the pad. This patent teaches that the rubber portion deposits a film on the rim which enables the leather portion to not slip. As with Everett and French Patent No. 818,322, French Patent No. 1,135,068, does not teach any manner for the individual user to selectively vary the frictional characteristics of the pad by selectively changing the various pad segments.
The present invention is intended to overcome one or more of the problems discussed above.